Method and apparatus to facilitate support for multi-radio coexistence

ABSTRACT

In a multi-radio user equipment, a power backoff or similar restraint may be placed on communications of a first radio, such as LTE, in order to protect operations of a second radio, such as Bluetooth, depending on the time remaining for completion of the communications of the second radio. Such protected operations may include paging or inquiry operations. A power backoff may be applied to an LTE radio in order to protect completion of the paging or inquiry operations. The power backoff may be increased as the time to completion of the paging or inquiry operations approaches.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional patentapplication No. 61/448,503 filed Mar. 2, 2011, in the names of LINSKY etal., the disclosure of which is expressly incorporated by reference inits entirety.

TECHNICAL FIELD

The present description is related, generally, to multi-radio techniquesand, more specifically, to coexistence techniques for multi-radiodevices.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE)systems, and orthogonal frequency division multiple access (OFDMA)systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. This communication linkmay be established via a single-in-single-out, multiple-in-single-out ora multiple-in-multiple out (MIMO) system.

Some conventional advanced devices include multiple radios fortransmitting/receiving using different Radio Access Technologies (RATs).Examples of RATs include, e.g., Universal Mobile TelecommunicationsSystem (UMTS), Global System for Mobile Communications (GSM), cdma2000,WiMAX, WLAN (e.g., WiFi), Bluetooth, LTE, and the like.

An example mobile device includes an LTE User Equipment (UE), such as afourth generation (4G) mobile phone. Such 4G phone may include variousradios to provide a variety of functions for the user. For purposes ofthis example, the 4G phone includes an LTE radio for voice and data, anIEEE 802.11 (WiFi) radio, a Global Positioning System (GPS) radio, and aBluetooth radio, where two of the above or all four may operatesimultaneously. While the different radios provide usefulfunctionalities for the phone, their inclusion in a single device givesrise to coexistence issues. Specifically, operation of one radio may insome cases interfere with operation of another radio through radiative,conductive, resource collision, and/or other interference mechanisms.Coexistence issues include such interference.

This is especially true for the LTE uplink channel, which is adjacent tothe Industrial Scientific and Medical (ISM) band and may causeinterference therewith. It is noted that Bluetooth and some Wireless LAN(WLAN) channels fall within the ISM band. In some instances, a Bluetootherror rate can become unacceptable when LTE is active in some channelsof Band 7 or even Band 40 for some Bluetooth channel conditions. Eventhough there is no significant degradation to LTE, simultaneousoperation with Bluetooth can result in disruption in voice servicesterminating in a Bluetooth headset. Such disruption may be unacceptableto the consumer. A similar issue exists when LTE transmissions interferewith GPS. Currently, there is no mechanism that can solve this issuesince LTE by itself does not experience any degradation

With reference specifically to LTE, it is noted that a UE communicateswith an evolved NodeB (eNB; e.g., a base station for a wirelesscommunications network) to inform the eNB of interference seen by the UEon the downlink. Furthermore, the eNB may be able to estimateinterference at the UE using a downlink error rate. In some instances,the eNB and the UE can cooperate to find a solution that reducesinterference at the UE, even interference due to radios within the UEitself. However, in conventional LTE, the interference estimatesregarding the downlink may not be adequate to comprehensively addressinterference.

In one instance, an LTE uplink signal interferes with a Bluetooth signalor WLAN signal. However, such interference is not reflected in thedownlink measurement reports at the eNB. As a result, unilateral actionon the part of the UE (e.g., moving the uplink signal to a differentchannel) may be thwarted by the eNB, which is not aware of the uplinkcoexistence issue and seeks to undo the unilateral action. For instance,even if the UE re-establishes the connection on a different frequencychannel, the network can still handover the UE back to the originalfrequency channel that was corrupted by the in-device interference. Thisis a likely scenario because the desired signal strength on thecorrupted channel may sometimes be higher be reflected in themeasurement reports of the new channel based on Reference SignalReceived Power (RSRP) to the eNB. Hence, a ping-pong effect of beingtransferred back and forth between the corrupted channel and the desiredchannel can happen if the eNB uses RSRP reports to make handoverdecisions.

Other unilateral action on the part of the UE, such as simply stoppinguplink communications without coordination of the eNB may cause powerloop malfunctions at the eNB. Additional issues that exist inconventional LTE include a general lack of ability on the part of the UEto suggest desired configurations as an alternative to configurationsthat have coexistence issues. For at least these reasons, uplinkcoexistence issues at the UE may remain unresolved for a long timeperiod, degrading performance and efficiency for other radios of the UE.

SUMMARY

According to one aspect of the disclosure, a method of communicating ina wireless network includes determining a time period remaining for anoperation by a first radio access technology (RAT). The method may alsoinclude applying a power backoff to a second RAT based on the timeperiod remaining.

According to another aspect of the disclosure, an apparatus forcommunicating in a wireless network includes means for determining atime period remaining for an operation by a first radio accesstechnology (RAT). The apparatus may also include means for applying apower backoff to a second RAT based on the time period remaining.

According to one aspect of the disclosure, an apparatus forcommunicating in a wireless network includes a memory and at least oneprocessor coupled to the memory. The processor(s) is configured todetermine a time period remaining for an operation by a first radioaccess technology (RAT). The processor(s) is further configured to applya power backoff to a second RAT based on the time period remaining.

According to another aspect of the disclosure, a computer programproduct for wireless communications in a wireless network includes acomputer-readable medium having non-transitory program code recordedthereon. The program code includes program code to determine a timeperiod remaining for an operation by a first radio access technology(RAT). The program code also includes program code to apply a powerbackoff to a second RAT based on the time period remaining.

Additional features and advantages of the disclosure will be describedbelow. It should be appreciated by those skilled in the art that thisdisclosure may be readily utilized as a basis for modifying or designingother structures for carrying out the same purposes of the presentdisclosure. It should also be realized by those skilled in the art thatsuch equivalent constructions do not depart from the teachings of thedisclosure as set forth in the appended claims. The novel features,which are believed to be characteristic of the disclosure, both as toits organization and method of operation, together with further objectsand advantages, will be better understood from the following descriptionwhen considered in connection with the accompanying figures. It is to beexpressly understood, however, that each of the figures is provided forthe purpose of illustration and description only and is not intended asa definition of the limits of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, nature, and advantages of the present disclosure willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout.

FIG. 1 illustrates a multiple access wireless communication systemaccording to one aspect.

FIG. 2 is a block diagram of a communication system according to oneaspect.

FIG. 3 illustrates an exemplary frame structure in downlink Long TermEvolution (LTE) communications.

FIG. 4 is a block diagram conceptually illustrating an exemplary framestructure in uplink Long Term Evolution (LTE) communications.

FIG. 5 illustrates an example wireless communication environment.

FIG. 6 is a block diagram of an example design for a multi-radiowireless device.

FIG. 7 is graph showing respective potential collisions between sevenexample radios in a given decision period.

FIG. 8 is a diagram showing operation of an example Coexistence Manager(C×M) over time.

FIG. 9 is a block diagram illustrating adjacent frequency bands.

FIG. 10 is a block diagram of a system for providing support within awireless communication environment for multi-radio coexistencemanagement according to one aspect of the present disclosure.

FIG. 11 is a block diagram illustrating progressive power backoff methodaccording to one aspect of the present disclosure.

FIG. 12 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

Various aspects of the disclosure provide techniques to mitigatecoexistence issues in multi-radio devices, where significant in-devicecoexistence problems can exist between, e.g., the LTE and IndustrialScientific and Medical (ISM) bands (e.g., for Bluetooth/WLAN). Asexplained above, some coexistence issues persist because an eNB is notaware of interference on the UE side that is experienced by otherradios. According to one aspect, the UE declares a Radio Link Failure(RLF) and autonomously accesses a new channel or Radio Access Technology(RAT) if there is a coexistence issue on the present channel. The UE candeclare a RLF in some examples for the following reasons: 1) UEreception is affected by interference due to coexistence, and 2) the UEtransmitter is causing disruptive interference to another radio. The UEthen sends a message indicating the coexistence issue to the eNB whilereestablishing connection in the new channel or RAT. The eNB becomesaware of the coexistence issue by virtue of having received the message.

The techniques described herein can be used for various wirelesscommunication networks such as Code Division Multiple Access (CDMA)networks, Time Division Multiple Access (TDMA) networks, FrequencyDivision Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA)networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms“networks” and “systems” are often used interchangeably. A CDMA networkcan implement a radio technology such as Universal Terrestrial RadioAccess (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) andLow Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and IS-856standards. A TDMA network can implement a radio technology such asGlobal System for Mobile Communications (GSM). An OFDMA network canimplement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11,IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM arepart of Universal Mobile Telecommunication System (UMTS). Long TermEvolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA,E-UTRA, GSM, UMTS and LTE are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). cdma2000is described in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). These various radio technologies andstandards are known in the art. For clarity, certain aspects of thetechniques are described below for LTE, and LTE terminology is used inportions of the description below.

Single carrier frequency division multiple access (SC-FDMA), whichutilizes single carrier modulation and frequency domain equalization isa technique that can be utilized with various aspects described herein.SC-FDMA has similar performance and essentially the same overallcomplexity as those of an OFDMA system. SC-FDMA signal has lowerpeak-to-average power ratio (PAPR) because of its inherent singlecarrier structure. SC-FDMA has drawn great attention, especially in theuplink communications where lower PAPR greatly benefits the mobileterminal in terms of transmit power efficiency. It is currently aworking assumption for an uplink multiple access scheme in 3GPP LongTerm Evolution (LTE), or Evolved UTRA.

Referring to FIG. 1, a multiple access wireless communication systemaccording to one aspect is illustrated. An evolved Node B 100 (eNB)includes a computer 115 that has processing resources and memoryresources to manage the LTE communications by allocating resources andparameters, granting/denying requests from user equipment, and/or thelike. The eNB 100 also has multiple antenna groups, one group includingantenna 104 and antenna 106, another group including antenna 108 andantenna 110, and an additional group including antenna 112 and antenna114. In FIG. 1, only two antennas are shown for each antenna group,however, more or fewer antennas can be utilized for each antenna group.A User Equipment (UE) 116 (also referred to as an Access Terminal (AT))is in communication with antennas 112 and 114, while antennas 112 and114 transmit information to the UE 116 over an uplink (UL) 188. The UE122 is in communication with antennas 106 and 108, while antennas 106and 108 transmit information to the UE 122 over a downlink (DL) 126 andreceive information from the UE 122 over an uplink 124. In an FDDsystem, communication links 118, 120, 124 and 126 can use differentfrequencies for communication. For example, the downlink 120 can use adifferent frequency than used by the uplink 118.

Each group of antennas and/or the area in which they are designed tocommunicate is often referred to as a sector of the eNB. In this aspect,respective antenna groups are designed to communicate to UEs in a sectorof the areas covered by the eNB 100.

In communication over the downlinks 120 and 126, the transmittingantennas of the eNB 100 utilize beamforming to improve thesignal-to-noise ratio of the uplinks for the different UEs 116 and 122.Also, an eNB using beamforming to transmit to UEs scattered randomlythrough its coverage causes less interference to UEs in neighboringcells than a UE transmitting through a single antenna to all its UEs.

An eNB can be a fixed station used for communicating with the terminalsand can also be referred to as an access point, base station, or someother terminology. A UE can also be called an access terminal, awireless communication device, terminal, or some other terminology.

FIG. 2 is a block diagram of an aspect of a transmitter system 210 (alsoknown as an eNB) and a receiver system 250 (also known as a UE) in aMIMO system 200. In some instances, both a UE and an eNB each have atransceiver that includes a transmitter system and a receiver system. Atthe transmitter system 210, traffic data for a number of data streams isprovided from a data source 212 to a transmit (TX) data processor 214.

A MIMO system employs multiple (NT) transmit antennas and multiple (NR)receive antennas for data transmission. A MIMO channel formed by the NTtransmit and NR receive antennas may be decomposed into NS independentchannels, which are also referred to as spatial channels, wherein NS≦min{NT, NR}. Each of the NS independent channels corresponds to adimension. The MIMO system can provide improved performance (e.g.,higher throughput and/or greater reliability) if the additionaldimensionalities created by the multiple transmit and receive antennasare utilized.

A MIMO system supports time division duplex (TDD) and frequency divisionduplex (FDD) systems. In a TDD system, the uplink and downlinktransmissions are on the same frequency region so that the reciprocityprinciple allows the estimation of the downlink channel from the uplinkchannel. This enables the eNB to extract transmit beamforming gain onthe downlink when multiple antennas are available at the eNB.

In an aspect, each data stream is transmitted over a respective transmitantenna. The TX data processor 214 formats, codes, and interleaves thetraffic data for each data stream based on a particular coding schemeselected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot datausing OFDM techniques. The pilot data is a known data pattern processedin a known manner and can be used at the receiver system to estimate thechannel response. The multiplexed pilot and coded data for each datastream is then modulated (e.g., symbol mapped) based on a particularmodulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for thatdata stream to provide modulation symbols. The data rate, coding, andmodulation for each data stream can be determined by instructionsperformed by a processor 230 operating with a memory 232.

The modulation symbols for respective data streams are then provided toa TX MIMO processor 220, which can further process the modulationsymbols (e.g., for OFDM). The TX MIMO processor 220 then provides NTmodulation symbol streams to NT transmitters (TMTR) 222 a through 222 t.In certain aspects, the TX MIMO processor 220 applies beamformingweights to the symbols of the data streams and to the antenna from whichthe symbol is being transmitted.

Each transmitter 222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. NTmodulated signals from the transmitters 222 a through 222 t are thentransmitted from NT antennas 224 a through 224 t, respectively.

At a receiver system 250, the transmitted modulated signals are receivedby NR antennas 252 a through 252 r and the received signal from eachantenna 252 is provided to a respective receiver (RCVR) 254 a through254 r. Each receiver 254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

An RX data processor 260 then receives and processes the NR receivedsymbol streams from NR receivers 254 based on a particular receiverprocessing technique to provide NR “detected” symbol streams. The RXdata processor 260 then demodulates, deinterleaves, and decodes eachdetected symbol stream to recover the traffic data for the data stream.The processing by the RX data processor 260 is complementary to theprocessing performed by the TX MIMO processor 220 and the TX dataprocessor 214 at the transmitter system 210.

A processor 270 (operating with a memory 272) periodically determineswhich pre-coding matrix to use (discussed below). The processor 270formulates an uplink message having a matrix index portion and a rankvalue portion.

The uplink message can include various types of information regardingthe communication link and/or the received data stream. The uplinkmessage is then processed by a TX data processor 238, which alsoreceives traffic data for a number of data streams from a data source236, modulated by a modulator 280, conditioned by transmitters 254 athrough 254 r, and transmitted back to the transmitter system 210.

At the transmitter system 210, the modulated signals from the receiversystem 250 are received by antennas 224, conditioned by receivers 222,demodulated by a demodulator 240, and processed by an RX data processor242 to extract the uplink message transmitted by the receiver system250. The processor 230 then determines which pre-coding matrix to usefor determining the beamforming weights, then processes the extractedmessage.

FIG. 3 is a block diagram conceptually illustrating an exemplary framestructure in downlink Long Term Evolution (LTE) communications. Thetransmission timeline for the downlink may be partitioned into units ofradio frames. Each radio frame may have a predetermined duration (e.g.,10 milliseconds (ms)) and may be partitioned into 10 subframes withindices of 0 through 9. Each subframe may include two slots. Each radioframe may thus include 20 slots with indices of 0 through 19. Each slotmay include L symbol periods, e.g., 7 symbol periods for a normal cyclicprefix (as shown in FIG. 3) or 6 symbol periods for an extended cyclicprefix. The 2L symbol periods in each subframe may be assigned indicesof 0 through 2L-1. The available time frequency resources may bepartitioned into resource blocks. Each resource block may cover Nsubcarriers (e.g., 12 subcarriers) in one slot.

In LTE, an eNB may send a Primary Synchronization Signal (PSS) and aSecondary Synchronization Signal (SSS) for each cell in the eNB. The PSSand SSS may be sent in symbol periods 6 and 5, respectively, in each ofsubframes 0 and 5 of each radio frame with the normal cyclic prefix, asshown in FIG. 3. The synchronization signals may be used by UEs for celldetection and acquisition. The eNB may send a Physical Broadcast Channel(PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH maycarry certain system information.

The eNB may send a Cell-specific Reference Signal (CRS) for each cell inthe eNB. The CRS may be sent in symbols 0, 1, and 4 of each slot in caseof the normal cyclic prefix, and in symbols 0, 1, and 3 of each slot incase of the extended cyclic prefix. The CRS may be used by UEs forcoherent demodulation of physical channels, timing and frequencytracking, Radio Link Monitoring (RLM), Reference Signal Received Power(RSRP), and Reference Signal Received Quality (RSRQ) measurements, etc.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) inthe first symbol period of each subframe, as seen in FIG. 3. The PCFICHmay convey the number of symbol periods (M) used for control channels,where M may be equal to 1, 2 or 3 and may change from subframe tosubframe. M may also be equal to 4 for a small system bandwidth, e.g.,with less than 10 resource blocks. In the example shown in FIG. 3, M=3.The eNB may send a Physical HARQ Indicator Channel (PHICH) and aPhysical Downlink Control Channel (PDCCH) in the first M symbol periodsof each subframe. The PDCCH and PHICH are also included in the firstthree symbol periods in the example shown in FIG. 3. The PHICH may carryinformation to support Hybrid Automatic Repeat Request (HARQ). The PDCCHmay carry information on resource allocation for UEs and controlinformation for downlink channels. The eNB may send a Physical DownlinkShared Channel (PDSCH) in the remaining symbol periods of each subframe.The PDSCH may carry data for UEs scheduled for data transmission on thedownlink. The various signals and channels in LTE are described in 3GPPTS 36.211, entitled “Evolved Universal Terrestrial Radio Access(E-UTRA); Physical Channels and Modulation,” which is publiclyavailable.

The eNB may send the PSS, SSS and PBCH in the center 1.08 MHz of thesystem bandwidth used by the eNB. The eNB may send the PCFICH and PHICHacross the entire system bandwidth in each symbol period in which thesechannels are sent. The eNB may send the PDCCH to groups of UEs incertain portions of the system bandwidth. The eNB may send the PDSCH tospecific UEs in specific portions of the system bandwidth. The eNB maysend the PSS, SSS, PBCH, PCFICH and PHICH in a broadcast manner to allUEs, may send the PDCCH in a unicast manner to specific UEs, and mayalso send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period.Each resource element may cover one subcarrier in one symbol period andmay be used to send one modulation symbol, which may be a real orcomplex value. Resource elements not used for a reference signal in eachsymbol period may be arranged into resource element groups (REGs). EachREG may include four resource elements in one symbol period. The PCFICHmay occupy four REGs, which may be spaced approximately equally acrossfrequency, in symbol period 0. The PHICH may occupy three REGs, whichmay be spread across frequency, in one or more configurable symbolperiods. For example, the three REGs for the PHICH may all belong insymbol period 0 or may be spread in symbol periods 0, 1 and 2. The PDCCHmay occupy 9, 18, 32 or 64 REGs, which may be selected from theavailable REGs, in the first M symbol periods. Only certain combinationsof REGs may be allowed for the PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. TheUE may search different combinations of REGs for the PDCCH. The numberof combinations to search is typically less than the number of allowedcombinations for the PDCCH. An eNB may send the PDCCH to the UE in anyof the combinations that the UE will search.

FIG. 4 is a block diagram conceptually illustrating an exemplary framestructure in uplink Long Term Evolution (LTE) communications. Theavailable Resource Blocks (RBs) for the uplink may be partitioned into adata section and a control section. The control section may be formed atthe two edges of the system bandwidth and may have a configurable size.The resource blocks in the control section may be assigned to UEs fortransmission of control information. The data section may include allresource blocks not included in the control section. The design in FIG.4 results in the data section including contiguous subcarriers, whichmay allow a single UE to be assigned all of the contiguous subcarriersin the data section.

A UE may be assigned resource blocks in the control section to transmitcontrol information to an eNB. The UE may also be assigned resourceblocks in the data section to transmit data to the eNodeB. The UE maytransmit control information in a Physical Uplink Control Channel(PUCCH) on the assigned resource blocks in the control section. The UEmay transmit only data or both data and control information in aPhysical Uplink Shared Channel (PUSCH) on the assigned resource blocksin the data section. An uplink transmission may span both slots of asubframe and may hop across frequency as shown in FIG. 4.

The PSS, SSS, CRS, PBCH, PUCCH and PUSCH in LTE are described in 3GPP TS36.211, entitled “Evolved Universal Terrestrial Radio Access (E-UTRA);Physical Channels and Modulation,” which is publicly available.

In an aspect, described herein are systems and methods for providingsupport within a wireless communication environment, such as a 3GPP LTEenvironment or the like, to facilitate multi-radio coexistencesolutions.

Referring now to FIG. 5, illustrated is an example wirelesscommunication environment 500 in which various aspects described hereincan function. The wireless communication environment 500 can include awireless device 510, which can be capable of communicating with multiplecommunication systems. These systems can include, for example, one ormore cellular systems 520 and/or 530, one or more WLAN systems 540and/or 550, one or more wireless personal area network (WPAN) systems560, one or more broadcast systems 570, one or more satellitepositioning systems 580, other systems not shown in FIG. 5, or anycombination thereof. It should be appreciated that in the followingdescription the terms “network” and “system” are often usedinterchangeably.

The cellular systems 520 and 530 can each be a CDMA, TDMA, FDMA, OFDMA,Single Carrier FDMA (SC-FDMA), or other suitable system. A CDMA systemcan implement a radio technology such as Universal Terrestrial RadioAccess (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) andother variants of CDMA. Moreover, cdma2000 covers IS-2000 (CDMA2000 1X),IS-95 and IS-856 (HRPD) standards. A TDMA system can implement a radiotechnology such as Global System for Mobile Communications (GSM),Digital Advanced Mobile Phone System (D-AMPS), etc. An OFDMA system canimplement a radio technology such as Evolved UTRA (E-UTRA), Ultra MobileBroadband (UMB), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSMare described in documents from an organization named “3rd GenerationPartnership Project” (3GPP). cdma2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). In an aspect, the cellular system 520 can include a number ofbase stations 522, which can support bi-directional communication forwireless devices within their coverage. Similarly, the cellular system530 can include a number of base stations 532 that can supportbi-directional communication for wireless devices within their coverage.

WLAN systems 540 and 550 can respectively implement radio technologiessuch as IEEE 802.11 (WiFi), Hiperlan, etc. The WLAN system 540 caninclude one or more access points 542 that can support bi-directionalcommunication. Similarly, the WLAN system 550 can include one or moreaccess points 552 that can support bi-directional communication. TheWPAN system 560 can implement a radio technology such as Bluetooth (BT),IEEE 802.15, etc. Further, the WPAN system 560 can supportbi-directional communication for various devices such as wireless device510, a headset 562, a computer 564, a mouse 566, or the like.

The broadcast system 570 can be a television (TV) broadcast system, afrequency modulation (FM) broadcast system, a digital broadcast system,etc. A digital broadcast system can implement a radio technology such asMediaFLO™, Digital Video Broadcasting for Handhelds (DVB-H), IntegratedServices Digital Broadcasting for Terrestrial Television Broadcasting(ISDB-T), or the like. Further, the broadcast system 570 can include oneor more broadcast stations 572 that can support one-way communication.

The satellite positioning system 580 can be the United States GlobalPositioning System (GPS), the European Galileo system, the RussianGLONASS system, the Quasi-Zenith Satellite System (QZSS) over Japan, theIndian Regional Navigational Satellite System (IRNSS) over India, theBeidou system over China, and/or any other suitable system. Further, thesatellite positioning system 580 can include a number of satellites 582that transmit signals for position determination.

In an aspect, the wireless device 510 can be stationary or mobile andcan also be referred to as a user equipment (UE), a mobile station, amobile equipment, a terminal, an access terminal, a subscriber unit, astation, etc. The wireless device 510 can be cellular phone, a personaldigital assistance (PDA), a wireless modem, a handheld device, a laptopcomputer, a cordless phone, a wireless local loop (WLL) station, etc. Inaddition, a wireless device 510 can engage in two-way communication withthe cellular system 520 and/or 530, the WLAN system 540 and/or 550,devices with the WPAN system 560, and/or any other suitable systems(s)and/or devices(s). The wireless device 510 can additionally oralternatively receive signals from the broadcast system 570 and/orsatellite positioning system 580. In general, it can be appreciated thatthe wireless device 510 can communicate with any number of systems atany given moment. Also, the wireless device 510 may experiencecoexistence issues among various ones of its constituent radio devicesthat operate at the same time. Accordingly, device 510 includes acoexistence manager (C×M, not shown) that has a functional module todetect and mitigate coexistence issues, as explained further below.

Turning next to FIG. 6, a block diagram is provided that illustrates anexample design for a multi-radio wireless device 600 and may be used asan implementation of the radio 510 of FIG. 5. As FIG. 6 illustrates, thewireless device 600 can include N radios 620 a through 620 n, which canbe coupled to N antennas 610 a through 610 n, respectively, where N canbe any integer value. It should be appreciated, however, that respectiveradios 620 can be coupled to any number of antennas 610 and thatmultiple radios 620 can also share a given antenna 610.

In general, a radio 620 can be a unit that radiates or emits energy inan electromagnetic spectrum, receives energy in an electromagneticspectrum, or generates energy that propagates via conductive means. Byway of example, a radio 620 can be a unit that transmits a signal to asystem or a device or a unit that receives signals from a system ordevice. Accordingly, it can be appreciated that a radio 620 can beutilized to support wireless communication. In another example, a radio620 can also be a unit (e.g., a screen on a computer, a circuit board,etc.) that emits noise, which can impact the performance of otherradios. Accordingly, it can be further appreciated that a radio 620 canalso be a unit that emits noise and interference without supportingwireless communication.

In an aspect, respective radios 620 can support communication with oneor more systems. Multiple radios 620 can additionally or alternativelybe used for a given system, e.g., to transmit or receive on differentfrequency bands (e.g., cellular and PCS bands).

In another aspect, a digital processor 630 can be coupled to radios 620a through 620 n and can perform various functions, such as processingfor data being transmitted or received via the radios 620. Theprocessing for each radio 620 can be dependent on the radio technologysupported by that radio and can include encryption, encoding,modulation, etc., for a transmitter; demodulation, decoding, decryption,etc., for a receiver, or the like. In one example, the digital processor630 can include a coexistence manager 640 that can control operation ofthe radios 620 in order to improve the performance of the wirelessdevice 600 as generally described herein. The coexistence manager 640can have access to a database 644, which can store information used tocontrol the operation of the radios 620. As explained further below, thecoexistence manager 640 can be adapted for a variety of techniques todecrease interference between the radios. In one example, thecoexistence manager 640 requests a measurement gap pattern or DRX cyclethat allows an ISM radio to communicate during periods of LTEinactivity. A gap pattern is defined herein as a pattern alternatingbetween periods of activity for a radio (e.g., LTE) and periods ofinactivity for the radio.

For simplicity, digital processor 630 is shown in FIG. 6 as a singleprocessor. However, it should be appreciated that the digital processor630 can include any number of processors, controllers, memories, etc. Inone example, a controller/processor 650 can direct the operation ofvarious units within the wireless device 600. Additionally oralternatively, a memory 652 can store program codes and data for thewireless device 600. The digital processor 630, controller/processor650, and memory 652 can be implemented on one or more integratedcircuits (ICs), application specific integrated circuits (ASICs), etc.By way of specific, non-limiting example, the digital processor 630 canbe implemented on a Mobile Station Modem (MSM) ASIC.

In an aspect, the coexistence manager 640 can manage operation ofrespective radios 620 utilized by wireless device 600 in order to avoidinterference and/or other performance degradation associated withcollisions between respective radios 620. Coexistence manager 640 mayperform one or more processes, such as those illustrated in FIGS. 11,13, and 14. By way of further illustration, a graph 700 in FIG. 7represents respective potential collisions between seven example radiosin a given decision period. In the example shown in graph 700, the sevenradios include a WLAN transmitter (Tw), an LTE transmitter (Tl), an FMtransmitter (Tf), a GSM/WCDMA transmitter (Tc/Tw), an LTE receiver (Rl),a Bluetooth receiver (Rb), and a GPS receiver (Rg). The fourtransmitters are represented by four nodes on the left side of the graph700. The four receivers are represented by three nodes on the right sideof the graph 700.

A potential collision between a transmitter and a receiver isrepresented on the graph 700 by a branch connecting the node for thetransmitter and the node for the receiver. Accordingly, in the exampleshown in the graph 700, collisions may exist between (1) the WLANtransmitter (Tw) and the Bluetooth receiver (Rb); (2) the LTEtransmitter (Tl) and the Bluetooth receiver (Rb); (3) the WLANtransmitter (Tw) and the LTE receiver (Rl); (4) the FM transmitter (Tf)and the GPS receiver (Rg); (5) a WLAN transmitter (Tw), a GSM/WCDMAtransmitter (Tc/Tw), and a GPS receiver (Rg).

In one aspect, an example coexistence manager 640 can operate in time ina manner such as that shown by diagram 800 in FIG. 8. As diagram 800illustrates, a timeline for coexistence manager operation can be dividedinto Decision Units (DUs), which can be any suitable uniform ornon-uniform length (e.g., 100 μs) where notifications are processed, anda response phase (e.g., 20 μs) where commands are provided to variousradios 620 and/or other operations are performed based on actions takenin the evaluation phase. In one example, the timeline shown in thediagram 800 can have a latency parameter defined by a worst caseoperation of the timeline, e.g., the timing of a response in the casethat a notification is obtained from a given radio immediately followingtermination of the notification phase in a given DU.

As shown in FIG. 9, Long Term Evolution (LTE) in band 7 (for frequencydivision duplex (FDD) uplink), band 40 (for time division duplex (TDD)communication), and band 38 (for TDD downlink) is adjacent to the 2.4GHz Industrial Scientific and Medical (ISM) band used by Bluetooth (BT)and Wireless Local Area Network (WLAN) technologies. Frequency planningfor these bands is such that there is limited or no guard bandpermitting traditional filtering solutions to avoid interference atadjacent frequencies. For example, a 20 MHz guard band exists betweenISM and band 7, but no guard band exists between ISM and band 40.

To be compliant with appropriate standards, communication devicesoperating over a particular band are to be operable over the entirespecified frequency range. For example, in order to be LTE compliant, amobile station/user equipment should be able to communicate across theentirety of both band 40 (2300-2400 MHz) and band 7 (2500-2570 MHz) asdefined by the 3rd Generation Partnership Project (3GPP). Without asufficient guard band, devices employ filters that overlap into otherbands causing band interference. Because band 40 filters are 100 MHzwide to cover the entire band, the rollover from those filters crossesover into the ISM band causing interference. Similarly, ISM devices thatuse the entirety of the ISM band (e.g., from 2401 through approximately2480 MHz) will employ filters that rollover into the neighboring band 40and band 7 and may cause interference.

In-device coexistence problems can exist with respect to a UE betweenresources such as, for example, LTE and ISM bands (e.g., forBluetooth/WLAN). In current LTE implementations, any interference issuesto LTE are reflected in the downlink measurements (e.g., ReferenceSignal Received Quality (RSRQ) metrics, etc.) reported by a UE and/orthe downlink error rate which the eNB can use to make inter-frequency orinter-RAT handoff decisions to, e.g., move LTE to a channel or RAT withno coexistence issues. However, it can be appreciated that theseexisting techniques will not work if, for example, the LTE UL is causinginterference to Bluetooth/WLAN but the LTE downlink does not see anyinterference from Bluetooth/WLAN. More particularly, even if the UEautonomously moves itself to another channel on the uplink, the eNB canin some cases handover the UE back to the problematic channel for loadbalancing purposes. In any case, it can be appreciated that existingtechniques do not facilitate use of the bandwidth of the problematicchannel in the most efficient way.

Turning now to FIG. 10, a block diagram of a system 1000 for providingsupport within a wireless communication environment for multi-radiocoexistence management is illustrated. In an aspect, the system 1000 caninclude one or more UEs 1010 and/or eNBs 1040, which can engage inuplink and/or downlink communications, and/or any other suitablecommunication with each other and/or any other entities in the system1000. In one example, the UE 1010 and/or eNB 1040 can be operable tocommunicate using a variety resources, including frequency channels andsub-bands, some of which can potentially be colliding with other radioresources (e.g., a broadband radio such as an LTE modem). Thus, the UE1010 can utilize various techniques for managing coexistence betweenmultiple radios utilized by the UE 1010, as generally described herein.

To mitigate at least the above shortcomings, the UE 1010 can utilizerespective features described herein and illustrated by the system 1000to facilitate support for multi-radio coexistence within the UE 1010.The various modules including the channel monitoring module 1012,resource coexistence analyzer 1014, RSSI sensing module 1016, and powerbackoff module 1018, as well as other modules may be configured toimplement the aspects discussed below. The various modules 1012-1018may, in some examples, be implemented as part of a coexistence managersuch as the coexistence manager 640 of FIG. 6. The various modules1012-1018 and others may be configured to implement the embodimentsdiscussed herein.

A Bluetooth device, in order to discover other devices, utilizes anoperation called inquiry. The purpose of a device inquiry is to collectinformation about other Bluetooth devices in proximity that might joinin a network with the inquiring device at some point in the future. Aninquiry operation may last for 10.24 seconds and is a relatively highduty cycle operation. Another high duty cycle Bluetooth operation,paging, establishes a connection between Bluetooth devices. The purposeof a device page is to invite a specific paged device to join a network.Paging typically lasts for a maximum of 5.12 seconds but mayautomatically terminate when the paged device responds.

Transmission by a Long Term Evolution (LTE) radio may interfere with theability of a Bluetooth radio to receive incoming signals. Suchinterference can de-sense a Bluetooth device such that paging/inquiryfails. It may be desired to protect specific Bluetooth operations, suchas inquiry and paging, by backing off LTE transmission power to reduceinterference to Bluetooth operations. It may not be desirable, however,to back off LTE power more than a certain amount, as such power backoffmay negatively impact LTE upload performance. Proposed in thisdisclosure are aspects to progressively backoff LTE transmission powerbased on the level of LTE interference and proximity of Bluetoothoperations to timeout, after which the Bluetooth operations will fail.

In a 5.12 second long Bluetooth page operation, there are fouropportunities (1.28 seconds each), for a page scanning device to hear apage request prior to timeout. The paging request may begin operationwithout any backoff imposed on LTE. During this early operation period(e.g., 1 second) data may be collected from the Bluetooth signalregarding its interference, approximated with, for example, an averagereceived signal strength indicator (RSSI) value. This average RSSI maybe compared with an average RSSI from when LTE was known not to beinterfering with Bluetooth operation. The non-interfered RSSI andinterfered RSSI may be compared to determine if LTE is causinginterference to Bluetooth. A threshold may be established to measureagainst the compared RSSIs. If they exceed the threshold, a decision toimplement power backoff against LTE may occur. Based on the RSSIcomparison, power backoff may be applied. For example, the RSSI valuemay drive a loop on LTE power backoff.

As the paging period continues and approaches page timeout, thethreshold may be altered to be even more aggressive in applying LTEbackoff to quiet potential interference to Bluetooth. Thus, the decisionto apply LTE backoff may be a combined function of the level ofinterference caused to the Bluetooth device by LTE, as well as the timeremaining in the Bluetooth operation before timeout. For example, in thelast period of paging (3.84-5.12 seconds), a maximum LTE power backoffmay be applied. In another aspect, the level of interference based onRSSI statistics may be more heavily weighted during certain periods ofoperation (for example a middle period during a paging operation), andremaining time to timeout may be more heavily weighted during otherperiods of operation (for example a final period before a pagingoperation). In another configuration, the higher the interference, thehigher the backoff. The above scheme may be applied for paging, inquiry,or other Bluetooth operations to be protected.

Progressive backoff may be applied as follows. For each receive attempt,the Bluetooth component may send an RSSI for each received half slot tothe coexistence manager. At the coexistence manager, the RSSI is passedto an infinite impulse response (IIR) filter that processes as follows,RSSIΘα RSSI+(1−α)RSSIwhere alpha (α) defines the amount of filtering desired and RSSI definesan average received signal strength indicator. Note that the aboveaveraging is over frequency and time.

The coexistence manager then calculates whether the LTE transmission isoverlapping with that particular half slot based on the level ofperceived interference indicated by the RSSI. If there is no LTEoverlapping (for example, LTE is not transmitting at the lower 10 MHz ofthe band), then that corresponding RSSI is identified as RSSI_(LTEoff)and passed to another IIR filter that processes as follows:RSSI _(LTEoff)Θα RSSI _(LTEoff)+(1−α)RSSI_(LTEoff)

With the above two filters, the average RSSI ( RSSI) value and alsoaverage RSSI value when LTE is off ( RSSI _(LTEoff)) are available. Forthe early period during paging and inquiry (e.g., the first opportunity(i.e, second)), the coexistence manager may take RSSI measurements asdiscussed above. When Bluetooth is in receive mode, the RSSImeasurements effectively measure interference, as Bluetooth is nottransmitting. At the end of the early period, if the LTE duty cycle ishigh during the early period such that there are not enough samples(less than N_RSSI_LTEoff samples, with an example default value of 30)to compute the RSSI _(LTEoff), and if RSSI>RSSI_thld_connection_setup,where RSSI_thld_connection_setup is a threshold RSSI establishedaccording to a connection setup, then the coexistence manager may set anLTE_power headroom report (PHR)_less backoff value to a maximum backofffor a time period (T_blank) (e.g., default 20 ms), such that thecoexistence manager may measure RSSI _(LTEoff). For this purpose, theallowed LTE maximum transmission (TX) power limit may beLTE_Power_Limit=worst_case_LTE_max PowerLimitwhere worst_case_LTE_maxPowerLimit is configurable, and may have anexample default value of 5 dBm.

At the start of the next period of paging/inquiry (e.g., the 2^(nd)second), the coexistence manager may identify LTE as the dominantinterferer if both of the following conditions hold:RSSI>RSSI_thld_connetion_setup  i.RSSI _(LTEoff)<RSSI_LTEoff_thld_connetion_setup  ii.where RSSI_thld_connection_setup is a threshold RSSI establishedaccording to a connection setup and whereRSSI_LTEoff_thld_connection_setup is a threshold RSSI establishedaccording to a connection setup when LTE is off.

At the start of the 2^(nd) second, once LTE is identified as the sourceof the dominant interference through the above interference assessment,the coexistence manager then sends an LTE_PHR_Backoff message to the LTEradio to begin progressively backing off LTE transmission power.

The power backoff may be based at least in part on the power headroomreport (PHR). The following loop may drive the power backoff such thatthe average RSSI converges to a target value(RSSI_tar_connection_setup). In the loop, Δ (n) represents a previouspower backoff value and Δ(n+1) represents the new power backoff level:Δ(n+1)=Δ(n)+μ_(RSSI) _(—) _(Connection) _(—) _(Setup)[ RSSI−RSSI_(—)tar_connection_setup]where μ_(RSSI) _(—) _(Connection) _(—) _(Setup) is a scaling factorchosen to adjust the loop for desired performance.

The μRSSI_Connection_Setup parameter enables power adjustment in a nextinterval to be emphasized or deemphasized. For example, asμRSSI_Connection_Setup gets larger, the power backoff applied in a nextperiod may be larger. Conversely, as μRSSI_Connection_Setup getssmaller, the power backoff applied in the next period may be smaller.This feature allows LTE implementations to adjust dynamically to solvingcoexistence issues.

The above loop will drive the average RSSI value ( RSSI) to converge toRSSI_tar_connection_setup. In the loop, an update occurs everyT_PHR_loop_RSSI_Connection_Setup, a time value chosen for the time toupdate the power headroom report loop (an example default may be set at20 ms).

As the time gets closer to the page timeout (e.g., 3.84-5.12 seconds),the coexistence manager may become more aggressive on power backoff, anduse the maximum power backoff:LTE_Power_Limit=worst_case_LTE_maxPowerLimit

Paging and inquiry may also occur while Bluetooth is engaged in otheractive connections (such as extended synchronous connections (eSCO) oractive control list (ACL)). The above procedure may also apply to thesescenarios. For active connection, there may be another separateinterference assessment and power control loop running. The connectedmode processes run independent of the connection setup process as activeconnection supports adaptive frequency hopping (AFH) while connectionsetup does not. If both connection setup and connected mode are runningpower control loops, then the minimum of the LTE transmission powerlimit from those two loops may be sent back to the LTE radio.

For inquiry, the interference assessment and power backoff (if LTE isidentified as the dominant interference) is applied for one in Ninquiries, where N is a parameter. This is because the inquiry may beperiodically controlled by the host. If LTE becomes active from sleepstate during the Bluetooth paging/inquiry process, to simplify thedesign, the maximum LTE power backoff (with PHR modification) is appliedwhen LTE is in a connected state:LTE_Power_Limit=worst_case_LTE_maxPowerLimit

FIG. 11 illustrates progressive LTE power backoff method according toone aspect of the present disclosure. In block 1102, a coexistencemanager determines a time period remaining for an operation by a firstradio access technology (RAT). In block 1104, a coexistence managerapplies power backoff to a second RAT based on the time periodremaining.

FIG. 12 is a diagram illustrating an example of a hardwareimplementation for an apparatus 1200 employing a progressive LTE powerbackoff system 1214. The progressive LTE power backoff system 1214 maybe implemented with a bus architecture, represented generally by a bus1224. The bus 1224 may include any number of interconnecting buses andbridges depending on the specific application of the progressive LTEpower backoff system 1214 and the overall design constraints. The bus1224 links together various circuits including one or more processorsand/or hardware modules, represented by a processor 1226, a determiningmodule 1202 and an applying module 1204, and a computer-readable medium1228. The bus 1224 may also link various other circuits such as timingsources, peripherals, voltage regulators, and power management circuits,which are well known in the art, and therefore, will not be describedany further.

The apparatus includes the progressive LTE power backoff system 1214coupled to a transceiver 1222. The transceiver 1222 is coupled to one ormore antennas 1220. The transceiver 1222 provides a means forcommunicating with various other apparatus over a transmission medium.The progressive LTE power backoff system 1214 includes the processor1226 coupled to the computer-readable medium 1228. The processor 1226 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium 1228. The software, when executedby the processor 1226, causes the progressive LTE power backoff system1214 to perform the various functions described supra for any particularapparatus. The computer-readable medium 1228 may also be used forstoring data that is manipulated by the processor 1226 when executingsoftware. The progressive LTE power backoff system 1214 further includesthe determining module 1202 for determining a time period remaining foran operation by a first radio access technology. The determining modulecan also be configured for determining a measurement of potentialinterference of the first RAT caused by the second RAT. The progressiveLTE power backoff system 1214 further includes the applying module 1204for applying a power backoff to a second RAT based on the time periodremaining. The applying module can also can also be configured forapplying the power backoff to the second RAT based on the measurement ofpotential interference. The determining module 1202 and the applyingmodule 1204 may be software modules running in the processor 1226,resident/stored in the computer readable medium 1228, one or morehardware modules coupled to the processor 1226, or some combinationthereof. The progressive LTE power backoff system 1214 may be acomponent of the UE 250 and may include the memory 272 and/or theprocessor 270.

In one configuration, the apparatus 1200 for wireless communicationincludes means for means for determining a time period remaining for anoperation by a first radio access technology (RAT). The means may be thecoexistence manager 640, the determining module 1202, the multi-radiowireless device 600 and/or the progressive LTE power backoff system 1214of the apparatus 1200 configured to perform the functions recited by thedetermining means. As described above, the progressive LTE power backoffsystem system 1214 may include the memory 232/272, and or the processor230/270. In another aspect, the aforementioned means may be any moduleor any apparatus configured to perform the functions recited by theaforementioned means.

The apparatus 1200 for wireless communication includes means for meansfor applying a power backoff to a second RAT based on the time periodremaining. The means may be the coexistence manager 640, the applyingmodule 1204, the multi-radio wireless device 600 and/or the progressiveLTE power backoff system 1214 of the apparatus 1200 configured toperform the functions recited by the applying means. As described above,the progressive LTE power backoff system 1214 may include the memory232/272, and or the processor 230/270. In another aspect, theaforementioned means may be any module or any apparatus configured toperform the functions recited by the aforementioned means.

The examples above describe aspects implemented in an LTE system.However, the scope of the disclosure is not so limited. Various aspectsmay be adapted for use with other communication systems, such as thosethat employ any of a variety of communication protocols including, butnot limited to, CDMA systems, TDMA systems, FDMA systems, and OFDMAsystems. Similarly, although the description is with respect toBluetooth, it should appreciated that the present disclosure is equallyapplicable to other technologies, e.g., WLAN. Similarly, although RSSIis described as the approximation of interference, other metrics couldsubstitute for or supplement RSSI.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an example of exemplary approaches. Based upondesign preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged while remainingwithin the scope of the present disclosure. The accompanying methodclaims present elements of the various steps in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the aspects disclosed herein may be implemented aselectronic hardware, computer software, or combinations of both. Toclearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

The previous description of the disclosed aspects is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these aspects will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other aspects without departing from the spirit or scope ofthe disclosure. Thus, the present disclosure is not intended to belimited to the aspects shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for wireless communications, comprising:determining a time period remaining before completion of an ongoingoperation by a first radio access technology (RAT); and applying a powerbackoff to a transmission of a second RAT based at least in part on thetime period remaining of the ongoing operation by the first RAT.
 2. Themethod of claim 1, further comprising: determining a measurement ofpotential interference of the first RAT caused by the second RAT; andapplying the power backoff to the transmission of the second RAT basedat least in part the measurement of potential interference.
 3. Themethod of claim 2, in which applying the power backoff to thetransmission of the second RAT is further based at least in part on themeasurement of potential interference when the measurement of potentialinterference exceeds a predetermined threshold.
 4. The method of claim2, in which applying the power backoff to the transmission of the secondRAT comprises increasing the power backoff when the measurement ofpotential interference increases.
 5. The method of claim 1, in which theapplied power backoff increases as the time period remaining decreases.6. The method of claim 5, in which the applied power backoff is amaximum permitted power backoff toward an end of the time period.
 7. Themethod of claim 1, in which the first RAT comprises Bluetooth and thesecond RAT comprises Long Term Evolution (LTE).
 8. The method of claim7, in which the operation comprises a paging operation or an inquiryoperation.
 9. An apparatus for wireless communications, comprising:determining module means for determining a time period remaining beforecompletion of an ongoing operation by a first radio access technology(RAT); and applying module means for applying a power backoff to atransmission of a second RAT based at least in part on the time periodremaining of the ongoing operation by the first RAT.
 10. The apparatusof claim 9 further comprising: determining module means for determininga measurement of potential interference of the first RAT caused by thesecond RAT; and applying module means for applying the power backoff tothe transmission of the second RAT based at least in part on themeasurement of potential interference.
 11. An apparatus for wirelesscommunications, comprising: a memory; and at least one processor coupledto the memory and configured: to determine a time period remainingbefore completion of an ongoing operation by a first radio accesstechnology (RAT); and to apply a power backoff to a transmission of asecond RAT based at least in part on the time period remaining of theongoing operation by the first RAT.
 12. The apparatus of claim 11, inwhich the at least one processor is further configured: to determine ameasurement of potential interference of the first RAT caused by thesecond RAT; and to apply the power backoff to the transmission of thesecond RAT based at least in part on the measurement of potentialinterference.
 13. The apparatus of claim 12 in which applying the powerbackoff to the transmission of the second RAT is further based at leastin part on the measurement of potential interference when themeasurement of potential interference exceeds a predetermined threshold.14. The apparatus of claim 12 in which applying the power backoff to thetransmission of the second RAT comprises increasing the power backoffwhen the measurement of potential interference increases.
 15. Theapparatus of claim 11 in which the applied power backoff increases asthe time period remaining decreases.
 16. The apparatus of claim 15 inwhich the applied power backoff is a maximum permitted power backofftoward an end of the time period.
 17. The apparatus of claim 11, inwhich the first RAT comprises Bluetooth and the second RAT comprisesLong Term Evolution (LTE).
 18. The apparatus of claim 17, in which theoperation comprises a paging operation or an inquiry operation.
 19. Acomputer program product for wireless communications in a wirelessnetwork, comprising: a non-transitory computer-readable medium havingnon-transitory program code recorded thereon, the program codecomprising: program code to determine a time period remaining beforecompletion of an ongoing operation by a first radio access technology(RAT; and program code to apply a power backoff to a transmission of asecond RAT based at least in part on the time period remaining of theongoing operation by the first RAT.
 20. The computer program product ofclaim 19, in which the program code further comprises: program code todetermine a measurement of potential interference of the first RATcaused by the second RAT; and program code to apply the power backoff tothe transmission of the second RAT based at least in part on themeasurement of potential interference.